Primary and secondary cutter bit arrangement and method of operation



' G. S. M DOWELL PRIMARY AND SECONDARY CUTTER BIT ARRANGEMENT March 7, 1967 AND METHOD-OF OPERATION 5 Sheets-Sheet 1 Filed May 22, 1964 \l: I M F 0 0 0 0 Q OMQ Q 0 0 0 0 N A TTORNEV March 7, 1967. 5, MCDOWELL 3,307,875

' PRIMARY AND SECONDARY CUTTER BIT ARRANGEMENT AND METHOD OF OPERATION 4 A 1 5 Sheets-Sheet 2 Filed May 22, 19 64 LINK NUMBERS o/mscr/o/v OF TRAVEL PRlM. SEC.

'INI ENTOR GLENN S. N1 DOWELL A T TORNEV T M rch 7, 1967 MCD WELL 3,307,875

7" PRIOR ART METHOD A PRIMARY AND SECONDARY CUTTER BIT ARRANGEMENT AND METHOD OF OPERATION 3 Sheets-Sheet 5 Filed ,Ma 22, 19 64 the mineral.

United States Patent 3,307,875 PRIMARY AND SECONDARY CUTTER BIT ARRANGEMENT AND METHGD OF OPERATION Glenn S. McDowell, Claremont, N.H., assignor to Joy Manufacturing Company, Pittsburgh, I'm, a corporation of Pennsylvania Filed May 22, 1964, Ser. No. 369,510 5 Claims. (Cl. 299-) This invention relates to a mining method and apparatus and more particularly to an arrangement of cutting elements for removing coal or other mineral from a solid vein of such material occurring in earth strata.

It is well known to employ a multiplicity of cutting elements such as cutter bits in a cutter chain, bit ring, or boring arm of a-continuous mining machine to remove coal or other mineral from a vein of such material. Such bits are spaced longitudinally of an orbital path in which they are forced to travel and are advanced at substantially right angles to the orbital path to attack and disintegrate Such cutter bits are normally spaced transversely of the path so that they form a kerf in the mineral of substantial cross sectional area from which the mineral has been removed. In mining apparatus of the prior art such bits have been advanced into the vein in the kerf forming operation with all of the bits at substantially the same level of advance. The cutter bit arrangement of the present invention contemplates the provision of a plurality of bits operating at a main level of advance and arranged in groups hereinafter referred to as primary bit groups comprising anywhere from five to ten bits per group. Between such primary bit groups according to the present invention there are inserted one or more secondary bits having a level of advance substantially behind the level of advance of the primary bits and so positioned, transversely of the kerf, that portions of the mineral not removed by the bits of a primary group (which portions are known as cores) would be struck by the secondary bits and removed from the kerf. It is of course possible with devices of the prior art to provide enough bits spaced transversely of the kerf so that all parts of the kerf will be removed and no cores formed. Such an arrangement, however, requires a great number of bits many of which have very little effect on the formation of the kerf and result in a production of an excessive amount of finer particles than may be desired.

The advantages resident in the bit arrangement of the present invention reside in the fact that each of the primary bits is fully effective in forming the kerf and the secondary bits, although spaced transversely of the kerf between the positions of the primary bits, also have a large efiect on the formation of the kerf since each one of the secondary bits comes into action only after the passage of at least two bits in each of the positions adjacent to the position of the secondary bits and consequently each secondary bit encounters a core portion which it can remove with a relatively small amount of energy eX- pended as compared to the amount of coal being removed from the vein.

This principle of the employment of primary and secondary bits is applicable not only to a cutter chain forming a single kerf, but to a plurality of cutter chains forming parallel adjacent kerfs wherein the primary bits form the adjacent kerfs transversely spaced relative to each other leaving a core portion in between the adjacent kerfs which core portion will be attacked and removed by secondary bits extending transversely beyond the primary bits, but again at a level of advance considerably behind the level of the primary bits. The same principle is also applicable to the placement of bits on boring arms.

It is therefore an object of this invention to provide a new and improved cutter bit arrangement.

It is another object of this invention to provide a new and improved cutter bit arrangement wherein groups of primary bits attacking a mineral vein form cores therebetween and secondary bits following such primary bits at a substantially lower level remove the cores formed by the primary bits.

It is a more specific object of this invention to provide a new and improved cutter bit arrangement wherein a plurality of primary bits in a given path is followed by a secondary bit in an adjacent path at a lower level of advance to remove a core portion remaining after the passage of the primary bits.

It is still another specific object of this invention to provide a cutter bit arrangement wherein groups of primary bits mounted for orbital motion in parallel paths at a given level of advance form parallel kerfs in a mineral vein leaving a core of unmined mineral between the kerfs and wherein secondary bits at a subtsantially lower level of advance orbiting in paths between the first mentioned parallel paths remove'at least major portions of the cores remaining after the kerfs were formed.

It is another specific object of this invention to provide a new and improved mining method employing primary and secondary bits in the manner hereinabove described.

These and other objects and advantages of this invention will become more readily apparent upon consideration of the following description and drawings in which:

FIGURE 1 is a side elevational view of a portion of a cutter chain having cutter bits therein positioned according to the principles of this invention;

FIGURE 2 is an end elevational view taken substantially on line 22 of FIGURE 1;

FIGURE 3 is an end elevation View taken substantially on line 3-3 of FIGURE 1;

FIGURE 4 is a diagrammatic representation of a plurality of bits illustrating the bit arrangement of this in vention;

FIGURE 5 is a fragmentary sectional view of a por tion of another chain constructed according to the principles of this invention;

FIGURE 6 is a bit position chart for a portion of a chain such as that illustrated in FIGURE 1;

FIGURE 7 is a fragmentary sectional view of the portion of a mineral vein as it would appear during kerf forming operations of the prior art method; and

FIGURE 8 is a fragmentary sectional view of a portion of a mineral vein as it would appear during kerf forming operations of a multiple chain continuous miner employing bits arranged according to the present invention.

In FIGURE 1 there is shown a portion of a cutter chain 40 constructed according to the principles of this invention and comprising a series of links shown as 1 through 9 in FIGURE 1 and diagrammed in FIGURE 6 for the bits in links 1 through 35 in order to show relative bit positions longitudinally of the chain and transversely of their direction of travel in orbital motion which in FIGURES 1 and 6 is from right to left as indicated by the arrows 46. The direction of advance of the chain 40 into a mineral vein would be upwardly as viewed in FIGURE 1 and such directions will be hereinafter referred to as the forward directions of orbital motion and of advance, respectively, with the opposite directions being indicated as rearward directions for the purposes of description. However, such directions are to be considered as descriptive only and not limitative upon the invention. As seen in FIG- URE 1, the chain 40 comprises a plurality of links 1-9 pivotably connected together by connectors 41 so that the chain 40 can be maintained in orbital motion by drive and idler sprockets (not shown) in a manner well known in the art. Each link is provided with a cutter bit 42 of a type suitable for the mineral being mined, individual bits being hereinafter referred to by the number of the link in which it is removably secured as by a set screw 44 or other suitable means. Two types of link are used in the chain 40, for example links 1 and of FIG. 1 are of the type shown in FIG. 2 and identified as link 1. The link 1 has a bit receiving socket therein which positions a bit vertically as in position A. Other links 2-5 of the same type have sockets for holding the bits in the oblique positions indentified as B, C, D and E respectively. A second type of link shown in FIG. 3 and indicated as link number 6 has a substantially lower profile and a socket for holding a bit in the W position while links '7, 13 and 14 are similar to link 6 except for having sockets suitable for holding bits in the positions X, Y and Z respectively.

The letters A, B, C, D, E, W, X, Y and Z as applied in FIGURES 1 through 3, 6 and 8 indicate the relative positions of the bits transversely of the direction of orbital motion. Such bit positions are definitely shown in FIG- URES 2, 3 and 8 and indicated diagrammatically in FIG- URE 6. The positions A through E are those assigned to primary bits as for example bits 1 through 5, 8 through 12, 15 through 19, and 22 through 26 as diagrammed in FIGURE 6 and partially shown in FIGURE 1. The positions W through Z are those occupied by secondary hits as for example bits 6, 7, 13, 14, 2t), 21, 27, 28, 34 and 35 (see FIG. 6). In FIGURE 1 it is to be seen that the bits 1 through 5 (primary bits) are ahead of the secondary bits 6 and '7 both in the direction of orbital motion to the left as viewed is FIGURE 1 and in the direction of advance, upwardly as viewed in FIGURE 1.

Referring now particularly to FIGURE 6, it is to be noted that a secondary bit as for instance bit in the W position is preceded by two bits 8 and 15 in the A position and bits 9 and 16 in the B position so that a core is formed within the kerf, as illustrated by the hatched portion W in FIGURE 8, before the link2 carrying a bit in the W position advances through the area occupied by the core W and removes a portion of the core W from the kerf. In like manner the bits 4 and 11 in the D position and the bits 2 and 9 in the B position precede the bit 13 in the Y position so that again a core portion indicated as Y is formed in the Y position before the bit in the link 13 travels through the area of the kerf to remove at least a portion of the core Y.

It is to be realized that the above described chain 459 is only illustrative of the principles of this invention as applied to a single chain and that the use of several primary bits on both sides of the path of the secondary bit before a secondary bit is found in a particular position is indicated as an application of the principles of this in vention and the fact that only two primary bits in each of the adjacent positions is shown should not be limiting upon this invention.

Further inspection of FIGURE 6 shows that after primary bits 1-5, one each in the five primary positions A through E, have passed through the kerf two secondary bits 6 and 7 in positions W and X, respectively, are ap* plied to remove portions of the cores in the W and X positions, then another five bits 8 through 12, in the pri' mary positions, form a second group of primary bits before the secondary bits 13 and 14, respectively, travel through the Y and Z positions after which the link 15 carrying a bit in the A position begins to repeat the cycle of primary and secondary groups so that as diagrammed in FIGURE 6 a total of fourteen bits makes up a single bit pattern of two identical primary bit groups and two different secondary bit groups. It is to be realized that the core portions W and Y would be considerably longer after the passage of two bits in the A, B and D positions, respectively, and such elongation of W and Y is shown by a dot and dash line representation to indicate the downward prolongation of W and Y, respectively, before the bits 13 and 20 pass through the W and Y positions, respectively.

The operation of the chain of FIGURES 1, 2, 3 and 6 is a continuous one with pairs of bits in the respective primary positions being followed by bits in the secondary position as above described so that there is a continuous process of the formation of cores such as W and Y between the paths of the primary bits and a continual removal of the lower portions of such cores by the bits in the secondary positions in a manner unique to the bit arrangement of this invention.

FIGURE 4 is a diagrammatic representation of the bit arrangement of this invention with the bits 51, 52, 53, 54 and 55 in primary positions and the bits 56, 57, 58 and 59 in secondary positions. The principles of this invention include the positioning of several bits in the 51 and 52 positions respectively relative to a single bit in the 56 position which number of primary bits will vary from the two described above through as many as five or six, depending upon the mineral being mined and the conditions under which the mining operation is being carried out, especially as regards the amount of power available and the size of mineral particles desired.

FIGURE 5 illustrates a fragment of a cutter chain '70 used on a multiple chain continuous miner and illustrates a different type of bit positioning wherein a central bit 61 and two bits 61 and 62 positioned to the right thereof as viewed in FIGURE 6 together with suitable bits (not shown) in position analogous to 61 :and 62, but to the left of the bit 66, form a set of primary bits in a kerf forming operation. After kerf formation has begun a bit 63 extending to the far righthand side of FIGURE 5 operates as a secondary bit at a lower level of advance to remove a core formed between the bit 62 and a similar though leftward extending bit 65 of a kerf forming chain (see FIG. 8) operating to the right of the chain 70 shown in FIGURE 5. As seen in FIGURE 8, a core 72 of the coal has been formed between the extreme righthand and lefthand primary bits 62 and 65 of the chains '71 and 80, respectively, the lower ends of the core 72 being shown in dotted and dashed outline indicating that a considerable portion of the core 72 will be removed by the action of the secondary bits 63 and 64 in the same manner as was described with relation to the secondary bits in the links 13 and 2t) occupying the W and Y positions, respectively.

The operation illustrated in FIGURE 8 is of course a continuous one and can be applied with or without the secondary bits in the positions W, X, Y and Z, depending upon the conditions of operation as hereinabove described.

When the secondary bits in the positions X, Y, and Z are eliminated, the primary bits in each chain of a set of parallel chains must be more closely spaced or more nearly aligned in the direction of orbital motion so that, at a given level of advance, clean kerfs are formed in a mineral vein with no need for secondary bits operating in paths between the primary bit paths within a single kerf. This arrangement leaves a larger core between the kerfs to be removed by secondary bits, such as bits 63 and 64 of FIG. 8 operating at a lower level of advance in paths between the kerfs. The advantages of this arrangement reside in the use of fewer bits within the kerf and a greater production of large fragments by the secondary bits, with a concomitant reduction in horsepower per ton of mined mineral.

FIGURE 7 is an illustration of the kerf conditions resulting from the application of the prior art bit arrangement wherein it is observable that a core portion 74 formed between a pair of chains carrying bits in a prior art arrangement is left undisturbed until contacted by either the bit blocks or by some portion of the chain supporting frame at which time a large amount of power will likely be necessary to remove the core portion 74.

Another core portion 76 formed between the extreme righthand bits in FIGURE 7 illustrates the situation when only relatively widely spaced primary bits are used wherein the core portion 76 extends downwardly far enough to be contacted by the chain links again causing a large amount of horsepower to be used in removal of a comparatively small amount of coal because of the rubbing action. of the links as distinguished from the cutting and breaking action characteristic of bit contact with the mineral. Furthermore, such rubbing action results in rapid wearing of the links and reduces the useful life of the chain.

It is to be noted that the description of the direction of advance as being substantially normal to a portion of the path of orbital motion includes: an approximately eliptical orbit with the direction of advance in the plane of the orbit (a cutter chain); a circular orbit with the direction of advance normal to the plane of the orbit (boring arms); as well as a circular orbit with the direction of advance in the plane of the orbit (bit rings). For the purposes of this invention the direction of advance is important only as to the positioning of the bits relative thereto and should not be taken as limiting the applications of the principles herein set forth.

It is further to be noted that the application of the principles of this invention to a chain having more than one bit in at least some of the blocks is envisioned as a desirable embodiment of these principles.

The advantages resident in the bit arrangement of the present invention are the use of fewer bits for a given size kerf; the requirement of less horsepower per cubic foot of mineral removed; the production of larger pieces of mineral than those produced by prior art bit arrangements and longer chain link life because of the absence of wear due to rubbing against uncut mineralwhich often occurs with bit arrangements of the prior art.

A preferred embodiment of this invention having been described, it is to be realized that variations in its application are envisioned and contemplated. Therefore, it is respectfully requested that the claims appended to this application be interpreted as broadly as possible and be limited only by the prior art.

I claim:

1. In a mining apparatus having a plurality of support elements movable in and spaced lengthwise of an orbital path and having a direction of advance substantially normal to a portion of such orbital path, an arrangement of cutting elements secured in such support elements wherein a plurality of primary cutting elements have respective primary cutting edges distributed in primary positions transversely across said path with spaces therebetween, said primary cutting edges being disposed along a surface defining a first level of advance and a plurality of secondary cutting elements have respective cutting edges spaced transversely across said path with said cutting edges of said secondary cutting elements distributed in positions aligned with said spaces and disposed along a surface defining a second level of advance substantially rearward of said first level of advance the improvement comprising: the arrangement of said cutting edges consisting of at least two of said cutting edges in one primary position preceding, with respect to movement in the orbital path, a cutting edge in a secondary position adjacent said one primary position.

2. In a mining apparatus having a plurality of support elements movable in and spaced lengthwise of an orbital path and having a direction of advance substantially normal to a portion of such orbital path, an arrangement of cutting elements secured in such support elements wherein a plurality of primary cutting elements have respective primary cutting edges distributed in primary positions transversely across said path with spaces therebetween, the tips of said cutting edges being disposed along an arcuate surface defining a first level of advance and a plurality of secondary cutting elements have respective cutting edges spaced transversely across said path with said cutting edges of said secondary cutting elements distributed in positions aligned with said spaces and the tips thereof disposed along an arcuate surface defining a second level of advance substantially rearward of said first level of advance the improvement comprising: the arrangement of said cutting edges consisting of at least two of said cutting edges in one primary position preceding with respect to movement in the orbital path a cutting edge in a secondary position adjacent said one primary position.

3. In a mining apparatus having a plurality of orbitable members, each member having a plurality of support elements movable in and spaced lengthwise of an orbital path and each member having a direction of advance substantially normal to a portion of such orbital path, said orbital paths being parallel to and spaced at intervals from each other, an arrangement of cutting elements secured in such support elements wherein a plurality of primary cutting elements in each member have respective primary cutting edges distributed in primary positions transversely across said path with spaces therebetween and with intervals between primary cutting edges of the said members, respectively, the tips of said primary cutting edges being disposed along a surface defining a first level of advance: a plurality of secondary cutting elements in each member having respective cutting edges spaced transversely across said path with said cutting edges of said secondary cutting elements distributed in positions aligned with said spaces and said intervals and the tips thereof disposed along a surface defining a second level of advance substantially rearward of said first level of advance the improvement comprising: the arrangement of said cutting edges in a repeating pattern of similar groups wherein each group consists of one of said secondary cutting elements in a secondary position spaced rearwardly, along the orbital path, of at least two primary cutting elements, in each of the primary positions adjacent said secondary position.

4. In a mining apparatus having a plurality of orbitable cutting chains, each chain having a plurality of support elements movable in and spaced lengthwise of an eliptical path and each chain having a direction of advance in the plane of such orbit and substantially normal to a portion of such orbital path, said planes being parallel to and laterally spaced at intervals from each other, an arrangement of cutting elements secured in such support elements wherein a plurality of primary cutting elements in each chain have respective primary cutting edges distributed in primary positions transversely across said path with intervals between primary cutting edges of the said chains, respectively, the tips of said primary cutting edges being disposed along a surface defining a first level of advance and a plurality of secondary cutting elements in each chain have respective cutting edges distributed in secondary positions aligned with said intervals and with the tips thereof disposed along a surface defining a second level of advance substantially rearward of said first level of advance the improvement comprising: the arrangement of said cutting edges in a plurality of repeating groups, each group consisting of at least two of said cutting edges in one primary position preceding with respect 7 8 0 movement in the orbital path a cutting edge in a References Cited by the Examiner :econdary position adjacent said one primary position. UNITED STATES PATENTS 5. A mining method in which a plurality of orbitally noving members ave cu ting edges sequentially engaging 1 IiI C E l 'tu l th t f; a" d mes 1 mlnera 111 S1 coflprlsmg e 8 p 0 c mg space 5 27832579 4/1958 Barrett 9 4 aortions of such mineral to form a plurality of elongated aterally spaced kerfs in said mineral with elongated free FOREIGN PATENTS edged cores of unmined mineral therebetween; subseuently cutting a second portion of minerals to deepen 155251 2/1953 Austraha' adjoining kerfs and increase the height of the core there- 10 ERNEST R PURSER Primary Examiner aetween; thereafter removing a major portion of said core from the free edge thereof. 

5. A MINING METHOD IN WHICH A PLURALITY OF ORBITALLY MOVING MEMBERS HAVE CUTTING EDGES SEQUENTIALLY ENGAGING A MINERAL IN SITU COMPRISING THE STEP OF: CUTTING SPACED PORTIONS OF SUCH MINERAL TO FORM A PLURALITY OF ELONGATED LATERALLY SPACED KERFS IN SAID MINERAL WITH ELONGATED FREE EDGED CORES OF UNMINED MINERAL THEREBETWEEN; SUBSEQUENTLY CUTTING A SECOND PORTION OF MINERALS TO DEEPEN ADJOINING KERFS AND INCREASE THE HEIGHT OF THE CORE THEREBETWEEN; THEREAFTER REMOVING A MAJOR PORTION OF SAID CORE FROM THE FREE EDGE THEREOF. 